Clinical Evaluation of a Dental Glass Ceramic: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Evaluation of a Dental Glass Ceramic (NCT04933123), a na na study. The primary outcome is Survival Rate of Inlays and Onlays.

2. Clinical Question

The clinical question is descriptive rather than comparative: what was recorded about the inlays and onlays after insertion in this group? Because there is no control group, the design cannot directly compare the restorations with another material or treatment. It also cannot separate changes related to the ceramic from changes related to other aspects of treatment or participants’ circumstances.

The registry describes the trial as intended to evaluate the safety and efficacy of an experimental glass ceramic. Its primary outcome is titled as a survival rate, while the listed outcome parameter is a number of inlays/onlays examined at the stated early assessment. The registry record does not provide a numerical survival result, a definition of failure, or a longer-term assessment schedule. Accordingly, the clinical question can be identified, but the posted record does not establish how many restorations met a survival criterion or how their performance changed over time.

3. Trial Design

This was a single-group device trial of indirect restorative treatment with a glass ceramic. The registry record lists 13 participants enrolled and describes inlays and onlays for molars and premolars, adhesively luted in shades A1, A2 and A3. The trial is marked terminated. Its recorded start date is 2021-09-14, and its primary completion date is 2021-11-15. The reason for termination is not reported in the registry record.

Allocation is listed as NA, and masking is listed as none. The record therefore does not describe randomized assignment or blinded assessment. The absence of a comparator is important: the design is not a like-for-like control comparison, and the single group cannot provide a direct estimate of a treatment difference. The trial is not assigned a conventional phase; its phase is listed as NA.

The primary outcome is titled “Survival Rate of Inlays and Onlays.” The record states that a dentist examined the restorations at baseline, defined as 7-10 days after insertion. A secondary outcome is listed as Quality Criteria (Modified FDI Criteria). The registry record does not provide detailed scoring instructions, a definition of restoration failure, or results for either outcome.

The listed enrollment describes the number of participants, while the primary outcome is expressed in terms of inlays/onlays. The number of restorations assessed and how multiple restorations within a participant were handled are not reported in the registry record. The record also does not describe eligibility criteria, recruitment details, protocol deviations, or the reason the trial was terminated. These omissions limit assessment of how the enrolled group was selected and how fully it represents the intended clinical population.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Survival Rate of Inlays and Onlays, measured over Baseline (7-10 days after insertion of restoration).

The primary outcome is titled “Survival Rate of Inlays and Onlays.” The registry record says a dentist examined the inlay and onlay restorations at baseline, 7-10 days after insertion, and lists the outcome parameter as a number of inlays/onlays. It does not report the numerical result. The record also does not define what counted as a restoration surviving, specify a failure event, or state whether survival was assessed only at that early visit or later as well.

In general, a survival endpoint is used to describe whether an item remains in place or has avoided a defined failure over a specified period. This is a general explanation, not a claim about the endpoint definition used in this trial. The definition and observation period matter because a count at an early assessment does not by itself describe durability over a longer period. Time-to-event methods also require information about when events occurred and how observation ended; such details are not reported in the registry record.

The early examination can describe the status recorded at that visit, but the record does not give enough information to interpret longer-term restoration performance. The secondary outcome, Quality Criteria (Modified FDI Criteria), is named, but its results and scoring details are not reported in the registry record. Neither outcome can be quantitatively interpreted from the posted results because no numerical outcome results are reported.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What can a single-group design estimate?

In general, a single-group study can describe the outcomes recorded among participants receiving the intervention. It does not directly estimate a difference between that intervention and a comparator because no separate comparison group is present. In this trial, the registry record lists indirect restorative treatment with a glass ceramic and describes a single arm. Allocation is listed as NA. The record therefore does not describe random assignment to competing treatments or a controlled comparison.

For a comparative effect, researchers need a contrast between groups or another clearly specified comparison. Without one, an outcome observed after treatment can be described, but the result cannot separate the intervention’s contribution from other influences. This is a general limitation of uncontrolled designs, not a claim about what caused any particular outcome in this trial. The numerical primary outcome is not reported in the registry record, so even a descriptive outcome value is unavailable.

What does the outcome label tell us?

The primary outcome is titled “Survival Rate of Inlays and Onlays,” has a number as its parameter, and is assessed at baseline, 7-10 days after insertion. A survival outcome generally needs a clear definition of what counts as survival and a specified period over which that status is evaluated. Those details affect the meaning of a result. For example, an early assessment and an assessment after extended follow-up address different periods of restoration performance. This is a general distinction; the registry record does not provide a longer-term schedule, a failure definition, or the numerical outcome.

The registry says a dentist examined the restorations. Masking is listed as none. In general, masking can reduce the possibility that knowledge of treatment influences assessment, especially when an outcome requires judgment. The record does not say whether the outcome was objectively defined or how examiner judgments were standardized. It also does not give the assessment form or a detailed scoring manual for the secondary Quality Criteria (Modified FDI Criteria) outcome.

How should uncertainty be understood?

In general, a confidence interval describes the range of effect estimates compatible with the data under a specified statistical model and assumptions. A narrow interval indicates greater precision than a wide interval; neither an interval nor a point estimate eliminates uncertainty. The registry record reports no primary outcome estimate, confidence interval, or analysis, so precision cannot be assessed for the primary endpoint. No statistical significance conclusion can be drawn from a result that is not reported.

When observations are clustered within participants, they may not be statistically independent. For example, a participant could contribute more than one restoration. Treating correlated restorations as independent can make uncertainty appear smaller than it is. This is a general statistical consideration; the registry record does not state how many restorations each participant contributed or how the analysis handled within-participant clustering. It reports no analysis details that would resolve this issue.

Similarly, the denominator for an outcome matters. Enrollment is reported as 13 participants, while the primary outcome is expressed as a number of inlays/onlays. The record does not report the number assessed for that endpoint or how missing observations were handled. A participant count should not automatically be treated as the number of independent restoration observations. The outcome result and its denominator are both needed for a clear interpretation.

What do planning illustrations mean?

Planning illustrations are not observed trial results or evidence of the study’s achieved power. The associated planning assumptions describe a hypothetical two-arm calculation with equal allocation, a two-sided significance level of 0.05, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. These are planning assumptions, not a description of this single-group trial’s allocation or an explanation of its actual design. Sample-size illustrations based on an observed effect are hypothetical planning exercises, not “observed power.” The registry record does not report a sample-size justification or identify those assumptions as the trial’s own design plan.

Power calculations in general depend on the target effect, variability, analysis method, and design assumptions. If the underlying observed effect is unavailable, a reader cannot assess the clinical relevance of a planning illustration that uses a fraction of that effect. The registry record does not report the primary outcome estimate needed to anchor such an effect. The planning assumptions therefore cannot fill in the missing outcome result or establish the precision of the study’s findings.

The registry record lists zero analyses. That means no statistical analyses are reported in the record; it does not establish what analyses may or may not have been conducted outside the posted record. The analysis plan, handling of missing observations, and analysis populations are not reported in the registry record. Consequently, readers cannot determine whether an analysis followed a prespecified plan, how uncertainty was calculated, or whether any adjustments were made.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists a primary outcome and a secondary outcome, but does not report statistical analyses or results for either. It does not specify whether there were additional outcome measures, repeated assessments, subgroup analyses, or multiple statistical tests beyond the outcomes named in the record. A multiplicity strategy, such as a prespecified method for interpreting several tests, is not reported in the registry record. With no reported inferential results, it is not possible to assess whether multiplicity affected any p-values or confidence intervals.

Missing-data methods are not reported in the registry record. The record does not state whether every enrolled participant completed the planned assessment, how missing outcome observations were handled, or whether any restorations were excluded. It also does not provide the number of restorations assessed for the primary outcome. Enrollment of 13 participants is reported, but this should not be assumed to equal the endpoint denominator, particularly because the endpoint counts inlays/onlays rather than participants.

The analysis populations are not reported in the registry record. There is no description of an intention-to-treat, per-protocol, or other analysis set. Those labels can have different meanings depending on the protocol and analysis, so none should be inferred from the record. The number of analyses reported is zero. This indicates that the registry record contains no analysis results; it does not establish whether analyses were performed elsewhere. These gaps prevent assessment of the handling of missing data, exclusions, and the relationship between the enrolled group and any analyzed group.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry record reports zero serious adverse events among 13 participants at risk, zero other adverse events among 13 participants at risk, and zero deaths. These are event counts as recorded for the trial; they are not comparative safety estimates because the study has no separate comparator group. The record does not provide individual event descriptions or further detail about how adverse events were collected.

A count of zero means no events in that category were reported in this record. It does not prove that an event was impossible, rule out events that were not captured, or establish safety over a longer period. The duration of safety observation and the methods for monitoring and attributing events are not reported in the registry record. The trial’s early primary assessment is described as 7-10 days after insertion, but the registry record does not specify whether safety monitoring continued for the same period or longer.

These counts should therefore be read as limited descriptive information for the 13 participants at risk, not as evidence from a controlled comparison or a complete characterization of safety. The registry record also does not report a reason for termination, so termination should not be interpreted as a safety signal.

12. What the Result Does, and Does Not, Mean

The record establishes that a clinical evaluation of a glass ceramic was registered as a single-group device trial, with 13 participants enrolled and an early dental examination of inlays and onlays planned or recorded as the primary assessment. It also lists a secondary quality-criteria outcome and reports zero serious adverse events, zero other adverse events, and zero deaths among 13 participants at risk. These registry entries describe the scope and the posted safety counts, but the record does not include numerical primary or secondary outcome results.

The record does not establish a numerical survival rate, the number of restorations that met a survival definition, or how precisely any outcome was estimated. The endpoint is assessed at baseline, 7-10 days after insertion, and no longer-term outcome result is reported. A short-term assessment should not be treated as evidence about performance over an unspecified longer period. The registry record also does not supply a failure definition or detailed follow-up schedule.

Because there is no comparator group, the trial cannot directly estimate how the glass ceramic compares with another material or treatment. The record does not describe randomization, and masking is listed as none. Even if a numerical within-group result were available, this design would not by itself show what would have occurred under an alternative treatment. No causal or comparative conclusion is supported by the posted information.

The absence of reported analyses also means there is no reported inferential estimate, confidence interval, or statistical test to interpret. The status is terminated, but the reason is not reported in the registry record. That status does not explain the findings or imply a particular safety or efficacy outcome. In short, the record describes the trial and some safety counts, but leaves the primary clinical result and its uncertainty unreported.

13. Why This Trial Matters Statistically

This trial illustrates why an outcome name alone is not enough to interpret a clinical result. “Survival Rate of Inlays and Onlays” sounds like a direct measure of restoration durability, but the registry record specifies an early assessment at baseline, 7-10 days after insertion and does not define failure or report a numerical result. The observation period and endpoint definition are central to what a survival measure can mean.

It also shows the distinction between a participant count and an outcome count. Enrollment is 13 participants, while the outcome is expressed as a number of inlays/onlays. If participants contribute more than one restoration, the observations may be related rather than independent. The registry record does not report the number of restorations or the approach to within-participant dependence. This makes clear why denominators and analysis methods matter when interpreting outcomes at the restoration level.

The single-group design is another important statistical feature. It can provide a description of observations in the enrolled group, but it does not create a direct comparison with another restoration. The allocation is listed as NA, and there is no comparator group. A treatment contrast, its uncertainty, and a conclusion about relative performance cannot be recovered from a design that does not report those comparisons.

Finally, the record distinguishes registration information from results. It identifies the trial as terminated and reports adverse-event counts, but gives neither the reason for termination nor numerical efficacy outcomes or analyses. This is a useful reminder that registry status, outcome definitions, observed results, and statistical inference answer different questions. Each needs to be considered separately, and missing information should not be replaced by assumptions.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The main trial-specific limitation is that the registry record does not report the numerical primary outcome result. Although the endpoint is titled survival rate and the assessment is described, neither the result nor its denominator is stated. The secondary Quality Criteria (Modified FDI Criteria) outcome is named without a numerical result or scoring details. The record therefore does not permit quantitative interpretation of either endpoint.

The stated primary assessment is baseline, 7-10 days after insertion. No later follow-up schedule or longer-term result is reported in the registry record, so durability beyond that early assessment cannot be assessed. A definition of restoration failure and the method used to determine survival are also not reported. The number of restorations assessed, whether participants contributed multiple restorations, and the handling of any missing observations are not reported.

The trial is single-group, has no reported randomized allocation, and lists no masking. It therefore lacks a direct comparator and may be vulnerable to influences that a controlled or masked design could help address. The record does not explain how the dentist’s assessments were standardized or whether the outcome criteria were objective. These are uncertainties about the design and measurement, not evidence that an assessment was biased.

The registry reports 13 participants enrolled and lists zero adverse events and deaths among 13 participants at risk, but does not specify the duration or procedures for safety monitoring. It also does not report the reason for termination, a sample-size justification, statistical analyses, missing-data methods, or analysis populations. Taken together, these omissions substantially limit interpretation of the trial beyond its basic design and posted safety counts.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Clinical Evaluation of a Dental Glass Ceramic — NCT04933123.
• Registry record last updated 2025-04-20; status last verified 2025-04.
• Results first posted 2025-04-02.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT04933123, titled “Clinical Evaluation of a Dental Glass Ceramic,” is a terminated, single-group device trial sponsored by Ivoclar Vivadent AG. The registry record reports 13 participants enrolled, a start date of 2021-09-14, and a primary completion date of 2021-11-15. Allocation is listed as NA and masking as none. The intervention is indirect restorative treatment with a glass ceramic in shades A1, A2 and A3.

The primary outcome is titled “Survival Rate of Inlays and Onlays,” with a dentist examination at baseline, 7-10 days after insertion. A secondary outcome is Quality Criteria (Modified FDI Criteria). Numerical results and statistical analyses are not reported in the registry record. The record lists zero serious adverse events, zero other adverse events, and zero deaths among 13 participants at risk. The reason for termination, longer-term follow-up, analysis populations, and missing-data methods are not reported in the registry record.